Use JSON patch for many VolumeSnapshot and VolumeSnapshotContent updates

[ggriffiths]

Signed-off-by: Grant Griffiths ggriffiths@purestorage.com

What type of PR is this?
/kind bug

What this PR does / why we need it:
This PR addresses the "object has been modified" issue we see a lot in the snapshot-controller/snapshotter.

Before this PR, we were seeing ~30-50 occurrences of this error in the snapshot-controller/snapshotter logs.

This PR only addresses the problematic areas found in the e2e PR tests. If we continue to see more of these errors, we can address replace the remaining Update/UpdateStatus calls in a separate PR.

Which issue(s) this PR fixes:
Fixes #525

Special notes for your reviewer:
n/a

Does this PR introduce a user-facing change?:

Replaces many VolumeSnapshot/VolumeSnapshotContent Update/UpdateStatus operations with Patch. This lowers the probability of the "object has been modified" update API errors occurring. This change introduces a dependency on two new RBAC rules for the snapshotter: volumesnapshotcontents:patch, volumesnapshotcontents/status:patch and four new RBAC rules for the snapshot-controller: volumesnapshotcontents:patch, volumesnapshotcontents/status:patch, volumesnapshots:patch, and volumesnapshots/status: patch.

[ggriffiths]

/hold

[ggriffiths]

50 error occurrences with MergePatchType as expected with ccfe3c7

$ curl -s https://storage.googleapis.com/kubernetes-jenkins/pr-logs/pull/kubernetes-csi_external-snapshotter/526/pull-kubernetes-csi-external-snapshotter-1-21-on-kubernetes-1-21/1397628215157067776/artifacts/kube-system/snapshot-controller-58f54d8f6c-btxgf/snapshot-controller.log | grep "object has been modified" | wc -l
50

Trying with JSONPatch now as suggested.

[ggriffiths]

JSONPatch seems to bring this count down for the one area I added it (updateContentErrorStatusWithEvent)

$ curl -s https://storage.googleapis.com/kubernetes-jenkins/pr-logs/pull/kubernetes-csi_external-snapshotter/526/pull-kubernetes-csi-external-snapshotter-1-21-on-kubernetes-1-21/1397649661208039424/artifacts/kube-system/snapshot-controller-58f54d8f6c-s46br/snapshot-controller.log | grep "object has been modified" | wc -l
34

[ggriffiths]

@xing-yang the latest PR tests have zero occurrences of the object has been modified API errors! Ready for review.

Thanks @bswartz for the JSON patch suggestion!

[ggriffiths]

/assign @xing-yang

[xing-yang]

Thanks @ggriffiths! This is great progress!

[ggriffiths]

Will squash these commits once an initial LGTM is given. Smallers commits have been useful while testing whether or not individual patch additions break the build.

[k8s-ci-robot]

@ggriffiths: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-kubernetes-csi-external-snapshotter-1-18-on-kubernetes-1-18	ab4503b	link	/test pull-kubernetes-csi-external-snapshotter-1-18-on-kubernetes-1-18

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[ggriffiths]

Ready for re-review @xing-yang

[xing-yang]

Good job @ggriffiths!

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ggriffiths, xing-yang

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